For example, Patent Document 1 discloses a technique for improving a visual perception of shift response by allowing a variation of the engine rotational speed displayed on a rotational speed display device faster than an actual rotational variation of the internal combustion engine at the time of shifting.
In Patent Document 1, when it is determined that an inertia phase is in place at the time of gear shifting, a subtraction of the turbine rotational speed at the initial gear stage from an actual rotational speed at the start of the inertial phase is added to a turbine rotational speed at a target gear shift, and the result thus calculated is used for the rotational speed for meter display.
However, when the actual change rate of the engine rotational speed is slower than the assumed rate, the change speed of the engine rotational speed for display becomes too faster than the change speed of the actual engine rotational speed. In this case, the deviation between the meter or display engine rotational speed and the engine sound or a vehicle acceleration variation becomes excessive, which may cause the driver to feel uncomfortable.